This invention relates to variable curvature optics and more particularly to variable curvature optics for counteracting the thermal lensing effects in laser rods.
When a solid state laser is operated, the center of the rod thereof heats up more than the outer portions of the rod such that the ends of the rod acquire a curvature which is a function of the thermal gradient within the rod. This curvature of the rod at the ends thereof will decrease the area of rod over which the TEM.sub.oo mode output will occur. Therefore, the total laser output would require a mask to permit only the TEM.sub.oo mode portion of the beam to pass through into the environment. This course of action, of course, is very inefficient since only a small portion of the available output is used.
Another solution to the problem is to grind the laser rod ends or the H.R. mirror into a properly shaped lens to compensate for the distortions created by the thermal lensing effects. This type of correction is only satisfactory for one laser power setting. When the laser is to be operated over a range of power settings this compensation will not suffice.